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A driver of a car travelling at 52 km h^–1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h^–1 in another car applies his brakes slowly and stops in 10 s.

Q 5.     A driver of a car travelling at 52 km h-1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h-1 in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

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The initial speed  =52\times \frac{5}{18}=14.4 \frac{m}{s}

After 5 sec the car stops

The graph is represented by the blue line ( x-axis is time and the y-axis is speed) 

For the car with 3Kmh-1. Initial speed =3\times\frac{5}{18}=0.833\frac{m}{s}  .  The graph which is represented by the golden line

The area covered by the blue graph is greater than the golden graph so the car with 15 m/s initial velocity travells large distance.

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